Add 'pkg/' from commit 'a11be4d7596203874b742b6597caf255204c56c3'

git-subtree-dir: pkg
git-subtree-mainline: dcf7368eea
git-subtree-split: a11be4d759

pkg/utils/utils.go

@@ -0,0 +1,41 @@
+// Copyright 2016 CNI authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package utils
+
+import (
+	"crypto/sha512"
+	"fmt"
+)
+
+const (
+	maxChainLength = 28
+	chainPrefix    = "CNI-"
+	prefixLength   = len(chainPrefix)
+)
+
+// Generates a chain name to be used with iptables.
+// Ensures that the generated chain name is exactly
+// maxChainLength chars in length
+func FormatChainName(name string, id string) string {
+	chainBytes := sha512.Sum512([]byte(name + id))
+	chain := fmt.Sprintf("%s%x", chainPrefix, chainBytes)
+	return chain[:maxChainLength]
+}
+
+// FormatComment returns a comment used for easier
+// rule identification within iptables.
+func FormatComment(name string, id string) string {
+	return fmt.Sprintf("name: %q id: %q", name, id)
+}